Noncommutative Geometry: Fuzzy Spaces, the Groenewold-Moyal Plane

In this talk, we review the basics concepts of fuzzy physics and quantum field theory on the Groenwald-Moyal Plane as examples of noncommutative spaces in physics. We introduce the basic ideas, and discuss some important results in these fields. In the end we outline some recent developments in the field.Comment: This is a contribution to the Proc. of the O'Raifeartaigh Symposium on Non-Perturbative and Symmetry Methods in Field Theory (June 2006, Budapest, Hungary), published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

What method of contact works best for recruiting participants in a study: lessons for health care researchers?

Objectives: To assess the various recruitment strategies used by medical researchers and their response rates. Methods: The observational study, part of a larger retrospective cohort, was done at the Aga Khan University Hospital, Karachi, Pakistan, from May 2008-December 2010, covering a period from 1999 to 2005. We used a multi-mode contact approach for including participants in the study. This comprised an invitational letter that described the study sent along with a mail-back, postage-paid envelope and multiple phone calls for recruitment of participants. The response to each mode was noted and described as frequency and percentage. Results: There were 1335 participants eligible for recruitment in the study. Of them, 1247 (93.4%) were sent mailouts to which only 84 (6.7%) responded. Besides, 1133 participants,whose phone numbers were available, were called. Overall, the number of people that we were able to contact was low. The response to postage paid mail was very poor whereas the majority of participants were contacted via phone calls. Out of such participants, 257 (19.25%) agreed to participate at the very first call and our results suggest that more than three calls made very little contribution to the consent rate. CONCLUSION: Recruiting subjects from contact information available in the medical records may not be the best method. Multiple and innovative approaches are required for approaching potential participants and requesting them to participate in a study

Combined Influence of Fly Ash and Recycled Coarse Aggregates on Strength and Economic Performance of Concrete

Recycled coarse aggregates (RCA) and fly ash (FA) are materials with least to very low global warming potential. Considering long term strength and durability, various studies have suggested to use RCA in concrete with FA. This research paper deals with the strength and economic performance of concrete made with individual and combined incorporation of FA and RCA. Nine different mixtures of concrete were prepared by varying the incorporation levels of RCA and FA. 0% RCA, 50% RCA and 100% RCA were used in concrete with three different levels of FA (0%FA, 20%FA, and 40%FA). The compressive strength of each mixture of concrete was determined at the age of 3, 28, 90 and 180 days. To evaluate economic performance cost of 1 m3 of each mixture of concrete was compared to that of the control mixture having 0% RCA and 0% FA. Results showed that RCA was detrimental to the compressive strength of concrete at all ages, whereas, FA reduced early strength but improved the strength at later ages of testing i.e. 90 and 180 days. FA plus RCA mixes also showed lower early age strength but gained higher strength than conventional concrete at the age of 180 days. RCA did not reduce the cost of concrete effectively. FA despite having a very high transportation cost, it reduced the cost of concrete efficiently. FA did not only reduce the cost of binder but also lower the demand of plasticizer by improving workability. Cost to strength ratio (CSR) analysis also indicated that FA significantly improve the combined economic and strength performance of RCA concrete mixes

Prevalence of diabetic retinopathy among individuals screened positive for diabetes in five community based eye camps in northern Karachi Pakistan

Background: Population-based data on the prevalence of diabetic retinopathy in Pakistan are lacking. We determined the prevalence of diabetic retinopathy among individuals screened positive for diabetes in five community-based eye camps in northern Karachi, Pakistan. Methods: In summer 2002, five community-based eye camps were set up in Karachi, Pakistan’s largest city. All individuals aged 30 years or older who visited the camps were requested to participate in the study. Those who agreed were screened for diabetes and those found to have the disease were referred to an eye hospital for diabetic retinopathy screening. Verbal informed consent was obtained from all participants at the examination site. Our main outcome measure was diabetic retinopathy, which was classified as non-proliferative diabetic retinopathy (NPDR), severe NPDR, and proliferative diabetic retinopathy (PDR). Our grading was based on clinical examination. Results: A total of 912 subjects were screened for diabetes mellitus. Of these, 160(17.5%) had diabetes- 1.8% had type I diabetes and 15.9% had type II diabetes. One hundred and eight individuals visited the hospital for ophthalmic examination. Of them, 15.7% had diabetic retinopathy. The prevalence of diabetic retinopathy was higher among individuals with type I diabetes, with greater duration of diabetes, and among women. The commonest form of diabetic retinopathy was non-proliferative (76.5% [mild: 35.3 %, moderate: 29.4 %, and severe: 11.8 %]), followed by maculopathy (17.6 %) and proliferative diabetic retinopathy (5.9 %). Conclusion: More systematic and population-based research is needed to estimate the prevalence of and identify risk factors for diabetic retinopathy in Pakista

Enhancing the Hardened Properties of Recycled Concrete (RC) through Synergistic Incorporation of Fiber Reinforcement and Silica Fume

Portland cement concrete is fragile in tension and it has numerous negative impacts on the environment. To deal with these issues, both fiber reinforcement and recycled materials can be utilized to manufacture sustainable and ductile concrete. In this study, the synergistic effects of high-performance mineral admixture silica fume and glass fiber reinforcement were investigated on the hardened properties of RC. For this purpose, two concrete mix families, namely, NC and RC were prepared. To understand the benefits of synergistic utilization of glass fiber and silica fume, in both NC and RC, 0.5% glass fiber was incorporated with three different levels of silica fume. i.e., 0%, 5%, and 10%. Both strength and permeability-related durability properties were investigated. Results revealed that combined incorporation of 0.5% fiber and 10% silica fume can help in the production of RC having better mechanical and durability performance compared to reference “NC”. Simultaneous incorporation of silica fume and glass fiber produces a combined effect greater than their individual effects on both mechanical and permeability properties of concrete. Silica fume plays a very dominant and positive role in the development of CS, WA, and CIPR of RC, whereas glass fiber plays a vital role in upgrading STS and FS of RC and whereas, with the addition of 0.5% glass fiber, RC can yield 8–9 times higher flexural toughness than that of the plain NC